Image motion sensitivity is a fundamental visual sense and a knowledge of its characteristics is likely to illuminate visual function in general. Using human psychophysical methods, we will address three topics in the coding of motions which could guide and complement physiological investigations. Specificallys we ask questions as to: 1) The existence and implications of orientation selectivity in motion processing. 2) The spatial and temporal frequency limitations in the early encoding of velocity magnitude. 3) The existence and temporal characteristics pf a hypothetical "velocity" intergrator. Our experiments will involve the discrimination of velocity direction and magnitude. Moving stimuli will include single and compound sinusoidal gratings, moving plane curves, and segmented lines moving into view behind circular windows.